R. Csuk et al. · Ring A-modified Glycyrrhetinic Acid Derivatives
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etate 7 : 3). – [α]D = 129.76◦ (c = 0.48, CHCl3). – UV/Vis (ddd, 1 H, J = 13.7, 13.7, 4.1 Hz, 16-H), 1.68 (ddd, H, J =
(methanol): λmax(logε) = 250 nm (4.04). – IR (KBr): ν = 12.7, 3.7, 3.7 Hz, 7-H), 1.62 (dd, 1 H, J = 13.4, 13.4 Hz,
3422br, 2958s, 2875m, 1718s, 1652s, 1466w, 1389m, 1361s, 19ꢀ-H), 1.56 (m, 1 H, 6-H), 1.49 (m, 1 H, 6ꢀ-H), 1.44 (m,
1276w, 1247w, 1219m, 1175s, 1155m, 1088w, 1031w, 931m, 1 H, 22-H), 1.42 (m, 1 H, 7ꢀ-H), 1.40 (m, 1 H, 22ꢀ-H), 1.36
913s, 880m cm−1. – 1H NMR (500 MHz, CDCl3): δ = 5.64 (s, 3 H, 27-H), 1.22 (s, 3 H, 29-H), 1.22 (m, 1 H, 16ꢀ-H),
(s, 1 H, 12-H), 4.37 (dd, 1 H, J = 11.8, 4.9 Hz, 3-H), 4.18 1.22 (m, 1 H, 21ꢀ-H), 1.16 (s, 3 H, 25-H), 1.16 (s, 3 H,
(dq, 1 H, J = 10.8, 7.1 Hz, Et-CHHꢀ), 4.11 (dq, 1 H, J = 26-H), 1.11 (dd, 1 H, J = 11.9, 2.4 Hz, 5-H), 1.03 (m, 1 H,
10.8, 7.1 Hz, Et-CHH’), 3.01 (s, 3 H, Mes-Me), 2.86 (ddd, 15ꢀ-H), 0.96 (s, 3 H, 23-H), 0.91 (s, 3 H, 24-H), 0.85 (s, 3 H,
1 H, J = 13.9, 3.7, 3.7 Hz, 1-H), 2.33 (s, 1 H, 9-H), 2.10 28-H). – 13C NMR (125 MHz, CDCl3): δ = 200.4 (C-11),
(ddd, 1 H, J = 13.7, 4.2, 1.1 Hz, 18-H), 2.02 (ddd, 1 H, 181.9 (C-30), 169.6 (C-13), 137.0 (C-3), 128.6 (C-12), 121.9
J = 13.9, 13.9, 4.2 Hz, 15-H), 1.99 (m, 1 H, 21-H), 1.97 (C-2), 60.5 (C-9), 51.8 (C-5), 48.2 (C-18), 45.4 (C-14), 43.8
(m, 1 H, 22-H), 1.92 (m, 1 H, 19-H), 1.89 (m, 1 H, 22ꢀ-H), (C-20), 43.3 (C-8), 41.5 (C-1), 40.9 (C-19), 37.7 (C-22), 36.2
1.82 (ddd, 1 H, J = 13.9, 13.9, 4.9 Hz, 16-H), 1.66 (m, (C-4), 34.3 (C-17), 31.9 (C-7), 31.9 (C-23), 31.8 (C-10),
1 H, 7-H), 1.60 (dd, 1 H, J = 13.5, 13.5 Hz, 19ꢀ-H), 1.60 30.9 (C-21), 28.6 (C-28), 28.4 (C-29), 26.5 (C-15), 26.4
(m, 1 H, 6-H), 1.47 (m, 1 H, 6ꢀ-H), 1.41 (ddd, 1 H, J = (C-16), 23.3 (C-27), 23.0 (C-24), 18.7 (C-6), 18.3 (C-26),
12.8, 2.7, 2.7 Hz, 7ꢀ-H), 1.38 (m, 1 H, 22-H), 1.35 (s, 3 H, 16.1 (C-25). – MS (ESI): m/z (%) = 453.5 (35) [M+H]+,
27-H), 1.32 (m, 1 H, 22ꢀ-H), 1.31 (m, 1 H, 21ꢀ-H), 1.25 (t, 475.4 (8) [M+Na]+, 507.0 (100) [M+MeOH+Na]+, 905.3
3 H, J = 7.1 Hz, Me), 1.17 (m, 1 H, 16ꢀ-H), 1.16 (s, 3 H, (18) [2M+H]+, 927.3 (40) [2M+Na]+.
25-H), 1.13 (s, 3 H, 29-H), 1.12 (s, 3 H, 26-H), 1.04 (s,
3 H, 23-H), 1.03 (m, 1 H, 1ꢀ-H), 0.97 (m, 1 H, 15ꢀ-H), 0.88
(s, 3 H, 24-H), 0.80 (m, 1 H, 5-H), 0.80 (s, 3 H, 28-H). –
13C NMR (125 MHz, CDCl3): δ = 199.7 (C-11), 176.3
(C-30), 169.5 (C-13), 128.4 (C-12), 90.1 (C-3), 61.6 (C-9),
60.3 (Et-CH2), 55.3 (C-5), 48.4 (C-18), 45.3 (C-8), 43.8
(C-20), 43.2 (C-14), 41.1 (C-19), 39.0 (Mes-Me), 38.8 (C-1
and C-4), 37.7 (C-22), 36.7 (C-10), 32.6 (C-7), 31.8 (C-17),
31.1 (C-21), 28.5 (C-28), 28.3 (C-29), 28.2 (C-23), 26.5
(C-16), 26.4 (C-15), 25.0 (C-2), 23.3 (C-27), 18.6 (C-26),
17.6 (C-6), 16.3 (C-24), 16.3 (C-25), 14.3 (Me). – MS
(ESI): m/z (%) = 577.4 (50) [M+H]+, 599.1 (100) [M+Na]+,
615.1 (4) [M+K]+, 887.8 (6) [3 M+2Na]2+, 1153.1 (18)
[2M+H]+, 1176.0 (17) [2M+Na]+, 1191.1 (2) [2M+K]+. –
C33H52O6S (576.83): calcd. C 75.26, H 9.08; found C 75.06,
H 9.23.
Methyl 11-oxo-olean-2,12-dien-30-oate (17)
To a solution of 14 (219 mg, 0.39 mmol) in dry DMF
(10 mL), tetrabutyl ammonium fluoride trihydrate (163 mg,
0.39 mmol) was added. After 4 d of stirring at between 100 –
105 ◦C, the solvent was removed under reduced pressure, and
the residue was subjected to chromatography (silica gel, hex-
ane / ethyl acetate 8 : 2) to yield 16 (92 mg, 51 %)◦as a color-
◦
less powder. M. p. 220 – 222 C (lit.: 224 – 228 C [13]). –
Rf = 0.81 (hexane / ethyl acetate 7 : 3). – [α]D = 209.85◦ (c =
0.33, CHCl3). – UV/Vis (methanol): λmax(logε) = 248 nm
(4.06). – IR (KBr): ν = 3438br, 2956s, 1728s, 1655s, 1617w,
1465m, 1385m, 1360w, 1328w, 1279w, 1259w, 1217m,
1156s, 1089w, 1029w cm−1. – 1H NMR (500 MHz, CDCl3):
δ = 5.67 (s, 1 H, 12-H), 5.42 (ddd, 1 H, J = 10.0, 5.8, 1.7 Hz,
2-H), 5.35 (dd, 1 H, J = 10.0, 2.1 Hz, 3-H), 3.67 (s, 1 H, Me),
3.03 (dd, 1 H, J = 17.4, 5.8 Hz, 1-H), 2.40 (s, 1 H, 9-H), 2.08
(ddd, 1 H, J = 13.7, 3.7, 1.3 Hz, 18-H), 2.01 (ddd, 1 H, J =
11-Oxo-olean-2,12-dien-30-oic acid (16)
A mixture of 13 (450 mg, 1.0 mmol) and potassium 13.7, 13.7, 4.2 Hz, 15-H), 1.98 (m, 1 H, 21-H), 1.91 (ddd,
carbonate (152 mg, 1.1 mmol) in dry DMF (10 mL) was 1 H, J = 13.7, 4.2, 2.5 Hz, 19-H), 1.82 (ddd, 1 H, J = 13.3,
stirred at 120 ◦C for 24 h. After removal of the solvent, 13.3, 4.2 Hz, 16-H), 1.68 (ddd, 1 H, J = 12.0, 12.0, 3.7 Hz,
aqueous work-up followed by extraction with CHCl3 (3 × 7-H), 1.64 (m, 1 H, 1ꢀ-H), 1.60 (dd, 1 H, J = 13.7, 13.7 Hz,
15 mL) and chromatography (silica gel, hexane / ethyl ac- 19ꢀ-H), 1.53 (m, 1 H, 6-H), 1.43 (m, 1 H, 6ꢀ-H), 1.41 (m, 1 H,
etate 8 : 2), 16 (200 mg,◦ 44 %) was obtained as colorless 7ꢀ-H), 1.38 (m, 1 H, 22-H), 1.35 (s, 3 H, 27-H), 1.30 (m, 2 H,
◦
crystals. M. p. 292 – 295 C (lit.: 290 – 296 C [13]). – Rf = 22ꢀ-H and 21ꢀ-H), 1.22 (m, 1 H, 16ꢀ-H), 1.15 (s, 3 H, 25-H),
0.50 (hexane / ethyl acetate 7 : 3). – [α]D = 209.79◦ (c = 1.14 (s, 3 H, 26-H), 1.13 (s, 3 H, 29-H), 1.10 (m, 1 H, 5-H),
0.66, CHCl3). – UV/Vis (methanol): λmax(logε) = 250 nm 1.00 (m, 1 H, 15ꢀ-H), 0.95 (s, 3 H, 23-H), 0.90 (s, 3 H, 24-H),
(4.08). – IR (KBr): ν = 3432br, 2950s, 2362w, 1699s, 1656s, 0.80 (s, 3 H, 28-H). – 13C NMR (125 MHz, CDCl3): δ =
1458m, 1386m, 1361w, 1328m, 1282w, 1260m, 1232m, 199.8 (C-11), 176.8 (C-30), 169.1 (C-13), 137.0 (C-3), 128.7
1209m, 1176m, 1088w, 1020w cm−1. – 1H NMR (500 MHz, (C-12), 122.0 (C-2), 60.6 (C-9), 52.0 (Me), 51.8 (C-5), 48.6
CDCl3): δ = 5.74 (s, 1 H, 12-H), 5.42 (ddd, 1 H, J = 9.8, 6.1, (C-18), 45.5 (C-14), 44.2 (C-20), 43.4 (C-8), 41.7 (C-1), 41.4
1.7, 2-H), 5.36 (dd, 1 H, J = 9.9, 2.1 Hz, 3-H), 3.04 (dd, 1 H, (C-19), 38.0 (C-22), 36.4 (C-9), 34.5 (C-10), 32.1 (C-7), 32.0
J = 17.5, 6.1 Hz, 1-H), 2.42 (s, 1 H, 9-H), 2.20 (dd, 1 H, (C-23), 32.0 (C-17), 31.3 (C-21), 28.7 (C-28), 28.5 (C-29),
J = 12.8, 3.5 Hz, 18-H), 2.03 (m, 1 H, 15-H), 2.00 (m, 1 H, 26.7 (C-16), 26.7 (C-15), 23.5 (C-27), 23.2 (C-24), 18.9
21-H), 1.94 (ddd, 1 H, J = 13.4, 4.1, 2.6 Hz, 19-H), 1.84 (C-6), 18.54 (C-26), 16.3 (C-25). – MS (ESI): m/z (%) =
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